1. Field of the Invention
This invention relates to a suspension comprising a microactuator element used in a disk drive for an information processing apparatus, such as a personal computer, and a manufacturing method therefor.
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing apparatus, such as a personal computer. The HDD comprises a magnetic disk rotatable about a spindle, a carriage turnable about a pivot, etc. The carriage, which comprises an actuator arm, is turned transversely relative to tracks of the disk about the pivot by a positioning motor, such as a voice coil motor.
A suspension is mounted on the actuator arm. The suspension comprises a load beam and flexure superposed thereon. A slider, which constitutes a magnetic head, is mounted on a gimbal portion formed near the distal end of the flexure. The slider is provided with elements (transducers) for accessing data, that is, for reading or writing data.
In order to overcome the increase in the recording density of disks, the magnetic head needs to be more accurately positioned relative to the recording surface of each disk. To attain this, a dual-stage-actuator (DSA) suspension has been developed that combines a positioning motor (voice coil motor) and microactuator. Examples of the DSA suspension are disclosed in Jpn. Pat. Appln. KOKAI Publications Nos. 2001-307442 (Patent Document 1) and 2002-50140 (Patent Document 2).
The microactuator comprises a piezoelectric element of lead zirconate titanate (PZT) or the like. An element accommodation portion is formed in an electrically conductive plate member that constitutes a part of the suspension. The microactuator element is located in the element accommodation portion. The microactuator element serves to move the distal end of the suspension finely in a sway direction (or transversely relative to tracks) at high speed. An electrical junction is provided between the conductive plate member and microactuator element.
The piezoelectric element of the DSA suspension is plate-like. A first electrode is disposed on one thicknesswise surface of the piezoelectric element, and a second electrode on the other surface. The first electrode is electrically connected to the conductive plate member as one conductive member through a conductive resin such as silver paste. The second electrode is connected to the other conductive member by a bonding wire or the like. The conductive resin comprises conductive filler particles, such as silver particles in a resin material. The conductive resin is cured after it is introduced to the junction.
Since the conductive resin is relatively viscous, air bubbles may sometimes be trapped in it as it is introduced to the conductive plate member. In addition, the air bubbles trapped in the conductive resin cannot be easily removed. In the conventional DSA suspension, the conductive resin is simply introduced to the junction of the conductive plate member. Therefore, the conductive resin, may fail to fully adhere to the conductive plate member, thereby causing conduction failure. In some cases, for example, a gap or hole may exist at the junction between the conductive resin and conductive plate member. In one such case, conduction failure was caused between the conductive plate member and microactuator element when a continuity test was conducted in a hot humid atmosphere.